Orthomorpha vietnamica, Likhitrakarn, Natdanai, Golovatch, Sergei I., Semenyuk, Irina, Efeykin, Boris D. & Panha, Somsak, 2019

Likhitrakarn, Natdanai, Golovatch, Sergei I., Semenyuk, Irina, Efeykin, Boris D. & Panha, Somsak, 2019, Review of the millipede genus Orthomorpha Bollman, 1893 (Diplopoda, Polydesmida, Paradoxosomatidae) in Vietnam, with several new records and descriptions of two new species, ZooKeys 898, pp. 121-158 : 121

Orthomorpha vietnamica sp. nov. Figs 15 , 16

Type material.

Holotype: ♂ (ZMUM Rd 4199), Vietnam, Gia Lai Province, Kon Ka Kinh National Park, near the village of Krong, 14°18'03"N, 108°26'42"E, 600 m a.s.l., mixed tropical forest, on tree trunk, night time, 9.V.2017, I. Semenyuk leg.

Paratype: 1 ♀ (ZMUM Rd 4200), same locality, together with holotype.

Name.

Adjective to refer to the country of origin.

Diagnosis.

This species seems to be especially similar to O. caramel sp. nov., but differs from all congeners ( Likhitrakarn et al. 2011) in the presence of a conspicuous, densely setose, rounded tubercle ( Fig. 16 , cxp) on the gonocoxa and the evident trifid tip of the solenophore, as well as the ♂ tarsal brushes showing until segment 16, coupled with the pleurosternal carinae present as complete crests with a sharp caudal tooth on segments 2-4.

Description.

Length 27.5 mm (♂) or 29.5 mm (♀), width of midbody pro- and metazonae 2.0 and 3.0 mm (♂) or 2.7 and 3.6 mm (♀), respectively.

Colouration of alcohol material after one year of preservation dark brown ( Fig. 10 B–H ); metaterga brown to light brownish; paraterga and epiproct light yellow to yellowish; legs and sterna light brown to pale yellow; head, collum, and antennae dark brownish to brown. Bases of paraterga marbled ( Fig. 15C ).

All characters as in O. caramel sp. nov., except as follows: clypeolabral region sparsely setose, vertigial region bare. Antennae rather short, reaching behind body segment 3 (♂, ♀) when stretched dorsally. In width, head <collum <segment 3 <4 <5 <2 <6-17 (♂) or head <collum <segment 3 <4 <2 <5-17 (♀), body gently and gradually tapering thereafter.

Tegument rather dull, prozonae finely shagreened, metaterga rugose to rugulose, surface below paraterga finely microgranulate and faintly rugulose ( Fig. 15 A–F ).

Axial line visible on collum and both on following pro- and metazonae.

Transverse sulcus usually distinct ( Fig. 15C, E, H ), complete on metaterga 5-18, incomplete and nearly wanting on segments 4 and 19, nearly line-shape, rather shallow, almost reaching the bases of paraterga, at most very faintly beaded at bottom.

Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2-4 (♂) ( Fig. 15B ) or nearly complete crests with a sharp caudal tooth on segment 4 (♀), thereafter bulged anteriorly and with a small sharp caudal tooth until segment 8, the tooth gradually reduced into small, caudally roughly granulate crests until segment 12 (♂, ♀). Epiproct ( Fig. 15F, G ) conical, flattened dorsoventrally, tip subtruncate; with two evident, sharp, apical teeth directed ventrocaudally (♂, ♀); pre-apical papillae very small, located close to tip. Hypoproct roundly subtriangular, setiferous knobs at caudal edge evident and well-separated ( Fig. 15G ).

Sterna sparsely setose, without modifications except for an evident, rounded, sparsely setose bulge directed anteroventrally between ♂ coxae 4 ( Fig. 15I, J ). A paramedian pair of evident, high tubercles in front of gonopod aperture. Legs rather long and slender, midbody ones ca. 1.2-1.3 (♂) or 0.8-0.9 (♀) times as long as body height, prefemora without modifications, ♂ tarsal brushes present until legs of segment 16.

Gonopods ( Fig. 16 ) somewhat more complex than usual. Coxa long and slender, with a conspicuous, high, laterally densely setose, rounded tubercle ( Fig. 16A, B , cxp). Femorite ca. 2 times as long as prefemoral (= strongly setose) part. Femorite slender, slightly curved and enlarged distad, “postfemoral” portion demarcated by an oblique lateral sulcus; solenophore with a tridentate tip, two subequal, rounded lobules (middle and ventral) and a shorter apicodorsal lobule; solenomere long and flagelliform, as usual.

Remarks.

We assume the apicodorsal lobule of the solenophore to be broken off, considering the structure of the solenophore tip in the other Orthomorpha spp.

The ecology of this species is very similar to that of O. caramel sp. nov. These two species are syntopic and share the same microhabitats.

Figures

Figure 10. Orthomorpha rotundicollis (Attems, 1937), subrotundicollis var. nov., ♂, left gonopod A, B mesal and lateral views, respectively C distal part, submesal view. Scale bars: 0.2 mm.

Figure 15. Orthomorpha vietnamica sp. nov., ♂ holotype A, B anterior part of body, dorsal and lateral views, respectively C, D segments 10 and 11, dorsal and lateral views, respectively E-G posterior part of body, lateral, dorsal and ventral views, respectively H, I sternal cones between coxae 4, subcaudal and sublateral views, respectively.

Figure 16. Orthomorpha vietnamica sp. nov., ♂ holotype, left gonopod A, B mesal and lateral views, respectively C, D tip of gonopod, submesal and sublateral views, respectively. Abbreviation: cxp, coxal tubercle. Scale bars: 0.5 mm.